Posterior corneal elevation appears to effectively discriminate keratoconus

This study's authors prospectively examined posterior corneal elevation using the Pentacam rotating Scheimpflug camera in one eye of 75 patients with keratoconus, 25 with subclinical keratoconus and 64 refractive surgery candidates with normal corneas. Mean posterior corneal elevation was significantly higher both in patients with keratoconus (100.7 µm) and subclinical keratoconus (39.9 µm) versus those with normal corneas (19.8 µm).

Based on receiver operating characteristic (ROC) curves, optimal cutoff points were estimated as 35 µm for keratoconus and 29 µm for subclinical keratoconus. This represented sensitivity and specificity for keratoconus of 97.3 percent and 96.9 percent, respectively, and 68 percent and 90.8 percent for subclinical keratoconus. The investigators concluded that posterior corneal elevation very effectively discriminates keratoconus from normal corneas but has lower efficacy for subclinical keratoconus and should not be used alone for making determinations regarding this condition.